Preparation of a thermoset resin system suitable for the preparation of fibre reinforced prepreg, the prepreg obtainable from the resin system, and its applications

Abstract

The present invention relates to polyisocyanate-based impregnating resin system, which is a liquid polyisocyanate mixture, containing more than 50% by weight MDI based di- and polyisocyanates, and one or more, originally powdery inorganic hydroxides. The resin system of the invention is suitable for the preparation of prepregs. The invention relates also to the prepreg that can be manufactured with the use of the resin system, and use thereof. Among the uses of the invention one important is the use of the prepreg for lining chimneys.

1 . Polyisocyanate based impregnating resin system, which is a liquid polyisocyanate mixture, containing more than 50% by weight MDI based di- and polyisocyanates, which polyisocyanates consist of raw P-MDI, polymer P-MDI homologs and isomers, MDI based prepolymers, modified MDIs, and the like, which resin additionally contains one or more, originally powdery inorganic hydroxides at an amount of less than 50% by weight, in suspended form. 
     
     
         2 . The resin system of  claim 1 , wherein the originally powdery inorganic hydroxide is a hydroxide, which does not release water around room temperature, but in the range of 90-110° C. provides water by reacting with the CO 2  released in during a water-isocyanate reaction. 
     
     
         3 . Resin system according to  claim 1  or  2 , wherein the inorganic hydroxide is Ca(OH) 2 , Mg(OH) 2  or Ba(OH) 2 , or any mixture thereof. 
     
     
         4 . Resin system according to any one of  claims 1 - 3 , wherein the Ca(OH) 2 , Mg(OH) 2  or Ba(OH) 2 , or any mixture thereof is present in at least 80% by weight in the inorganic hydroxide. 
     
     
         5 . Resin system according to any one of  claims 1 - 4 , wherein the inorganic hydroxide powder contains magnesium hydroxide carbonate (4MgCO 3 Mg(OH) 2 ·5H 2 O), CaO or MgO or similar as impurity, accompanying material and/or water retaining agent. 
     
     
         6 . Resin system according to any one of  claims 1 - 5 , wherein the resin system contains at most 40% by weight amount of inert filler, related to the total amount of the resin system. 
     
     
         7 . Resin system according to  claim 6 , wherein the inert filler is fine-grained calcium carbonate, magnesium carbonate, dolomite, quartz, graphite or talc or similar, or any mixture thereof. 
     
     
         8 . Use of the resin system according to any one of  claims 1 - 7 , for the preparation of prepreg. 
     
     
         9 . Process for the preparation of prepreg, characterized in that a substructure material is impregnated with the resin system according to any one of  claims 1 - 7 , using any of the known prepreg making methods, in the course of the impregnation siliconized paper layer is put to the impregnated substructure material, the material obtained this way is rolled to paper core tubes, and finally provided with water-vapour tight packaging. 
     
     
         10 . Process according to  claim 9 , characterized that impregnation is carried out at 30-70° C. resin system temperature. 
     
     
         11 . Process according to any one of  claim 9  or  10 , characterized that the speed of impregnation is 0.5-50 m/min, preferably 5-15 m/min. 
     
     
         12 . Process according to any of  claims 9 - 11 , characterized that glass-cloth or polyester fabric is used as substructure material. 
     
     
         13 . Process according to any of  claims 9 - 12 , characterized that the water-vapour tight package is a two- or multi-layered packaging material provided with an aluminium layer, or a water-vapour tight, tube-like capsule. 
     
     
         14 . Process for chimney lining, characterized that the resin system of the invention is used in the prepreg used for lining, wherein the following steps are used in the process: from the prepreg prepared by the use of the resin system suitable size hoses are formed with one of the methods known, and an extruded, one- or multi-layered heat-treatment hose is put inside the prepreg hose, a polyester calibrating hose is pulled to the double-walled hose obtained this way, finally the three-layered hose is introduced into the chimney flue, clamped to the necessary fittings, the prepreg hose is inflated with the heat-treatment hose, and the temperature necessary for curing is provided with the heat-treatment hose mentioned, by blowing through the hose hot steam, mixture of steam and air, or mixture of flue and steam. 
     
     
         15 . Method according to  claim 14 , wherein curing is performed at a temperature of 90-110° C., for 0.5-5 hours, preferably for 1-2 hours.